22.5.3.3 Sleep Mode Controller
Sleep mode is entered by executing the Wait For Interrupt instruction (WFI). The Sleep Mode bits in the Sleep Configuration register (SLEEPCFG.SLEEPMODE) select the level of the sleep mode.
Note: A small latency happens between the
store instruction and actual writing of the SLEEPCFG register due to bridges. Software
must ensure that the SLEEPCFG register reads the desired value before issuing a WFI
instruction.
Note: After power-up, the MAINVREG low power
mode takes some time to stabilize. Once stabilized, the SUPC->STATUS.ULPVREFRDY bit
is set. Before entering Standby, software must ensure that the
SUPC->STATUS.ULPVREFRDY bit is set.
| Mode | Mode Entry | Wake-Up Sources |
|---|---|---|
| IDLE | SLEEPCFG.SLEEPMODE = IDLE | Synchronous (2) (APB, AHB), asynchronous (1) |
| STANDBY | SLEEPCFG.SLEEPMODE = STANDBY | Synchronous(3), Asynchronous |
| OFF | SLEEPCFG.SLEEPMODE = OFF | External Reset |
Note:
- Asynchronous: interrupt generated on generic clock, external clock, or external event.
- Synchronous: interrupt generated on the APB clock.
- Synchronous interrupt only for peripherals configured to run in standby.
Note: The type of wake-up sources (synchronous or asynchronous) is given in each module
interrupt section.
The sleep modes (idle, standby and off) and their effect on the clocks activity, the regulator and the NVM state are described in the table and the sections below. Refer to Power Domain Controller for the power domain gating effect.
| Mode | Main clock | CPU | AHBx and APBx clock | GCLK clocks | Oscillators | VDDCORE Regulator | VDDPLL Regulator | NVM | |
|---|---|---|---|---|---|---|---|---|---|
| ONDEMAND = 0 | ONDEMAND = 1 | ||||||||
| Active | Run | Run | Run | Run(3) | Run | Run if requested | MAINVREG | ON(4) | active |
| IDLE | Run | Stop | Stop(1) | Run(3) | Run | Run if requested | MAINVREG | ON(4) | active |
| STANDBY | Stop(1) | Stop | Stop(1) | Stop(1) | Run if requested or RUNSTDBY=1 | Run if requested | MAINVREG in low power mode | ON(5) | Ultra Low- power |
| OFF | Stop | Stop | Stop | OFF | OFF | OFF | OFF | OFF | OFF |
Note:
- Running if requested by peripheral during SleepWalking.
- Running during SleepWalking.
- Following On-Demand Clock Request principle.
- Running if enabled (SUPC.VREGPLL.ENABLE = 1)
- Running if enabled (VREGPLL.ENABLE = 1) and allowed to run in Standby sleep mode: (SUPC.VREGPLL.RUNSTDBY = 1) or (SUPC.VREGPLL.RUNSTDBY = 0) and following the sleep walking request. SUPCVREG.RUNSTDBY must be set to allow VREGPLL running in Standby sleep mode. Refer to OSCCTRL module for details on oscillators behavior in STANDBY sleep mode.